import { on, off } from 'element-ui/src/utils/dom'
import { renderThumbStyle, BAR_MAP } from './util'

/* istanbul ignore next */
export default {
  name: 'Bar',

  props: {
    vertical: Boolean,
    size: String,
    move: Number,
  },

  computed: {
    bar() {
      return BAR_MAP[this.vertical ? 'vertical' : 'horizontal']
    },

    wrap() {
      return this.$parent.wrap
    },
  },

  render(h) {
    const { size, move, bar } = this

    return (
      <div
        class={['el-scrollbar__bar', 'is-' + bar.key]}
        onMousedown={this.clickTrackHandler}
      >
        <div
          ref="thumb"
          class="el-scrollbar__thumb"
          onMousedown={this.clickThumbHandler}
          style={renderThumbStyle({ size, move, bar })}
        ></div>
      </div>
    )
  },

  methods: {
    clickThumbHandler(e) {
      // prevent click event of right button
      if (e.ctrlKey || e.button === 2) {
        return
      }
      this.startDrag(e)
      this[this.bar.axis] =
        e.currentTarget[this.bar.offset] -
        (e[this.bar.client] -
          e.currentTarget.getBoundingClientRect()[this.bar.direction])
    },

    clickTrackHandler(e) {
      const offset = Math.abs(
        e.target.getBoundingClientRect()[this.bar.direction] -
          e[this.bar.client],
      )
      const thumbHalf = this.$refs.thumb[this.bar.offset] / 2
      const thumbPositionPercentage =
        ((offset - thumbHalf) * 100) / this.$el[this.bar.offset]

      this.wrap[this.bar.scroll] =
        (thumbPositionPercentage * this.wrap[this.bar.scrollSize]) / 100
    },

    startDrag(e) {
      e.stopImmediatePropagation()
      this.cursorDown = true

      on(document, 'mousemove', this.mouseMoveDocumentHandler)
      on(document, 'mouseup', this.mouseUpDocumentHandler)
      document.onselectstart = () => false
    },

    mouseMoveDocumentHandler(e) {
      if (this.cursorDown === false) return
      const prevPage = this[this.bar.axis]

      if (!prevPage) return

      const offset =
        (this.$el.getBoundingClientRect()[this.bar.direction] -
          e[this.bar.client]) *
        -1
      const thumbClickPosition = this.$refs.thumb[this.bar.offset] - prevPage
      const thumbPositionPercentage =
        ((offset - thumbClickPosition) * 100) / this.$el[this.bar.offset]

      this.wrap[this.bar.scroll] =
        (thumbPositionPercentage * this.wrap[this.bar.scrollSize]) / 100
    },

    mouseUpDocumentHandler(e) {
      this.cursorDown = false
      this[this.bar.axis] = 0
      off(document, 'mousemove', this.mouseMoveDocumentHandler)
      document.onselectstart = null
    },
  },

  destroyed() {
    off(document, 'mouseup', this.mouseUpDocumentHandler)
  },
}
